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Apple Scab (Venturia inaequalis)

Wednesday May 20, 2020

Apple Scab on Gala apples
Apple scab on leaves

Apple Scab (Venturia inaequalis)

Why is it a problem?
The incidence of apple scab has been increasing in a number of orchards in the Okanagan area, with increased levels showing up in the packinghouse. Scab can either present itself as in the traditional lesions or 'scabs' on the fruit or leaves, or can appear while in storage as pinpoint scab. Since the occurrence of scab on apples unfortunately makes the fruit unmarketable, growers should be aware of how to control for scab in order to avoid significant loses to their crop.  
 
Where does Scab come from?
Apple scab is a fungus that overwinters on the leaf litter in the orchard as ascospores, which with moisture such as rainfall or irrigation events, can be released from the orchard floor and land on the developing green tissue, causing a scab infection. What this means is that Growers should be concerned with and aware of potential scab infection periods occurring from Green tip, through Bloom and into the Fruitlet timing.    
 
How the BC DAS system can help: Keeping you Informed + Equipped
The BC Das system allows growers to be informed about scab infection periods, based on the growers' specific geographic location. Using the date for Green tip that the grower has inputted into the DAS system for their specific orchard block, the BC DAS will then incorporate up to date information from local weather stations throughout the valley, to notify growers when conditions are ideal for a scab infection to occur. Information such as average temperature, cumulative wetness hours, and the upcoming forecast will prompt the system to send out notifications to alert growers of past, current or upcoming scab infection periods.  
 
In addition, the BC Das system has control measures incorporated into the Scab model webpage. What this means is, when an alert for scab infection occurs, the grower is then supplied with the tools needed to ensure coverage against this disease. The DAS Spray Guide offers spray options for both protectant (before a scab infection) and eradicant (after a scab infection) products, as well as allowing the grower to select for products currently registered for either conventional or organic use. By following along on the BC DAS model, the grower will have timely information and knowledge of the tools currently available to prevent scab infections compromising their crop.    
 
Still interested in finding out more? Check out our video on the BC DAS Scab Model on YouTube to connect horticultural knowledge from the field with the online program: